The applicants proposed to study the potential of crystalline silicon x-ray detectors for digital mammography. These produce an electronic charge signal directly from the energy of interacting x rays and promise to offer significant performance advantages over existing screen-film technology and over phosphor-based imaging systems. A small format detector (64x64 elements) would be constructed to evaluate important detector properties for x-ray imaging, such as quantum efficiency, noise, linearity, uniformity as well as the performance of the time delay integration (TDI) charge readout mechanism. Based on findings from these experiments, the design would be refined and a larger device produced and tested. Appropriate signal processing algorithms to provide seamless matching of overlapping detector fields would be developed and evaluated at this stage. A multi-unit slot detector would then be built and incorporated onto a scanning gantry to produce full-field digital mammographs of high spatial resolution. Preliminary studies will also be conducted on the feasibility of other, higher atomic number materials for future detectors. This project is a collaboration which brings the mammographic physics and clinical expertise of the Imaging Research group at Sunnybrook Health Science Centre, University of Toronto together with the innovative approach to high resolution detectors developed by NOVA corporation.